For many applications it is desirable to form color images. A variety of techniques have been developed to form color images, including printing techniques and other imaging techniques such as thermal imaging processes.
Among the thermal imaging processes are “thermal transfer” processes in which heat is used to move colored material from a donor sheet to a receiver sheet. Alternatively, heat may be used to convert a colorless coating on a sheet into a colored image in a process called “direct thermal” imaging. Generally in this process a thermal print head is used to address one line of the image at a time.